Long Island weather: Sunny, very hot Sunday and Monday

A heat advisory will begin Sunday and last through Monday night as temperatures are forecast to hit 90 degrees both days on Long Island, a meteorologist with the National Weather Service said.

But it will likely feel hotter.

The advisory starts at noon Sunday and will continue until 8 p.m. Monday because indexes that measure how hot it feels could hit 100, the weather service said.

Sunday's forecast high is 90, and it's expected to reach 91 Monday.

Bill Goodman, a weather service meteorologist, said the temperature won't set record highs.

But staying indoors in air conditioning is recommended — especially for anyone whose health is frail. 

In a statement, Nassau County Executive Laura Curran said hours will be extended for county pools at Wantagh Park and Cantiague Park  from 10 a.m. to 7 p.m. for Sunday and Monday in anticipation of the heat. 

The risk of heat exhaustion is not the only reason to avoid the outdoors. High ozone is another hazard: Suffolk officials noted the state Department of Environmental Conservation issued an air quality health advisory for Sunday for lower New York State including Long Island and the metropolitan area. 

Suffolk County Health Commissioner Dr. Gregson Pigott in a statement said: "Ozone levels are often elevated after noon through early evening on hot, sunny days."

On Monday, the heat could feel worse than Sunday’s, though storms might bring a touch of cool. 

Tuesday should offer fair weather with a high of about 88 degrees, but it will be followed by a potentially stormy Wednesday as the odds of downpours are 50%, according to the weather service. Wednesday’s temps should top out at 83 degrees.

Temperatures Saturday reached a high of 88 degrees, the weather service said, and beaches along the South Shore quickly filled to capacity.